These are: 1) To continue our former comparisons of infantile with adult psychopathology; to clarify the interaction between innate endowment and environmental influence; to study aggressive, destructive and uncontrollable behaviour in children. 2) To extend our investigations from individual children to two clinical groups, i.e. those with identical overt symptomatology and those under the impact of identical potentially pathogenic influences. 3) To test the assumption that identical manifest symptoms can stem from a variety of underlying causes and that, conversely, identical pathogenic processes can give rise to a variety of widely different symptoms.